506
- 50601 Ackley
- 50602 Allison
- 50603 Alta Vista
- 50604 Aplington
- 50605 Aredale
- 50606 Arlington
- 50607 Aurora
- 50609 Beaman
- 50611 Bristow
- 50612 Buckingham
- 50613 Cedar Falls
- 50616 Charles City
- 50619 Clarksville
- 50620 Colwell
- 50621 Conrad
- 50622 Denver
- 50624 Dike
- 50625 Dumont
- 50626 Dunkerton
- 50627 Eldora
- 50628 Elma
- 50629 Fairbank
- 50630 Fredericksburg
- 50632 Garwin
- 50633 Geneva
- 50634 Gilbertville
- 50635 Gladbrook
- 50636 Greene
- 50638 Grundy Center
- 50641 Hazleton
- 50642 Holland
- 50643 Hudson
- 50644 Independence
- 50645 Ionia
- 50647 Janesville
- 50648 Jesup
- 50650 Lamont
- 50651 La Porte City
- 50652 Lincoln
- 50653 Marble Rock
- 50654 Masonville
- 50655 Maynard
- 50658 Nashua
- 50659 New Hampton
- 50660 New Hartford
- 50662 Oelwein
- 50664 Oran
- 50665 Parkersburg
- 50666 Plainfield
- 50667 Raymond
- 50668 Readlyn
- 50669 Reinbeck
- 50670 Shell Rock
- 50671 Stanley
- 50672 Steamboat Rock
- 50673 Stout
- 50674 Sumner
- 50675 Traer
- 50676 Tripoli
- 50677 Waverly
- 50680 Wellsburg
- 50681 Westgate
- 50682 Winthrop